原生JavaScript 瀑布流 实现 zx-waterfall

摘要：源码地址使用说明注意参数瀑布流外容器瀑布流宽度，如果初始化时外容器未隐藏状态则需使用该参数默认获取外容器宽度子元素选择器，比如样式名元素间的间隔元素间垂直方向间隔，默认使用值元素宽度默认会根据容器宽度自动调整强制元素宽度，

源码地址： https://github.com/capricornc...

Install zx-waterfall using npm

npm i --save zx-waterfall

ES6+

import ZxWaterfall from "zx-waterfall"

const waterfall = new ZxWaterfall({
  // HTMLElement, waterfall items"s outer container
  container: document.getElementById("zxWaterfall"),
  // children item selector, eg. ".item-container"
  itemSelector: ".item-wrapper",
  // item"s spacing, unit px
  gutter: 20,
  // item"s width
  itemWidth: 300
})
// reset
waterfall.reset()
// loaMedias
waterfall.loadMedia(["http://xx.com/aaa.jpg"]).then(_ => {
  // change
  waterfall.change()
})

browser

https://capricorncd.github.io...

container "s style must be style.position=relative|absolute|fixed

container: HTMLElement

瀑布流外容器.

containerWidth: Number

瀑布流宽度，如果初始化时外容器未隐藏状态则需使用该参数.

默认获取外容器宽度.

itemSelector: String

子元素选择器，比如 样式名".item-container".

gutter: Number

元素间的间隔.

verticalGutter: Number

元素间垂直方向间隔，默认使用gutter值.

itemWidth: Number

元素宽度, 默认 300, 会根据容器宽度自动调整.

forceItemWidth: Boolean

强制元素宽度，即使用itemWidth作为宽度值，默认 false.

align: String, Optional value left|center|right

强制宽度时，元素显示靠边位置，默认 center.

reset()

重置瀑布流初始值

loadMeida(array)

预加载列表数据中的image媒体元素.

array: ["http://a.com/1.jpg", "http://a.com/2.jpg"]

@return promise

change()

列表数据改变后后，通知瀑布流更新元素位置.

/**
 * preload image
 * @param url
 * @param handler
 */
function loadImage (url, handler) {
  let $el = document.createElement("img")
  $el.src = url
  $el.onload = handler
  $el.onerror = handler
  $el = null
}

/**
 * to int
 * @param m
 * @returns {number}
 */
function int (m) {
  let n = parseInt(m)
  return isNaN(n) ? 0 : n
}

/**
 * convert pseudoArray to array
 * @param pseudoArray
 * @param index
 * @returns {T[]}
 */
function slice (pseudoArray, index) {
  return Array.prototype.slice.call(pseudoArray, int(index))
}

// default options
const DEF_OPTIONS = {
  // HTMLElement, waterfall items"s outer container
  container: null,
  // container"s width, container are hidden when initialized
  // default get container offsetWidth when it"s visible
  containerWidth: 0,
  // children item selector, eg. ".item-container"
  itemSelector: "",
  // item"s spacing, unit px
  gutter: 20,
  // item"s vertical spacing, default use gutter"s value
  verticalGutter: 0,
  // item"s width
  itemWidth: 300,
  // force item width
  forceItemWidth: false,
  // Horizontal align when forceItemWidth is true
  align: "center"
}

/**
 * ZxWaterfall
 */
class ZxWaterfall {
  /**
   * constructor
   * @param opts
   */
  constructor (opts) {
    opts = Object.assign({}, DEF_OPTIONS, opts)
    // check container
    if (!opts.container || opts.container.nodeType !== 1) {
      throw new TypeError(`Instancing parameter "container" is not HTMLElement.`)
    }
    // check itemSelector
    if (!opts.itemSelector || typeof opts.itemSelector !== "string") {
      throw new TypeError(`Instancing parameter "itemSelector" is null or is"t a string.`)
    }
    // check verticalGutter
    if (!opts.verticalGutter) {
      opts.verticalGutter = opts.gutter
    }
    // item number
    this.count = 0
    this.opts = opts
    this._init()
    // clone this.reset
    this._resetClone = this.reset.bind(this)
    window.addEventListener("resize", this._resetClone)
  }

  /**
   * initialization
   * @private
   */
  _init () {
    let opts = this.opts
    // container width
    let containerWidth = int(opts.containerWidth) || opts.container.offsetWidth
    // column number
    let columnNum = Math.floor(containerWidth / (opts.itemWidth + opts.gutter))
    // opts.itemWidth when opts.forceItemWidth = true
    // else use compute new width
    this.itemWidth = opts.forceItemWidth
      ? opts.itemWidth
      : (containerWidth - (columnNum + 1) * opts.gutter) / columnNum
    // column current height array
    this.columns = Array(columnNum)
    this.columns.fill(0, 0)
    // offset left when forceItemWidth=true
    this.offsetLeft = 0
    if (opts.forceItemWidth) {
      let residualSpaceWidth = containerWidth - (this.itemWidth + opts.gutter) * columnNum - opts.gutter
      switch (opts.align) {
        case "center":
          this.offsetLeft = residualSpaceWidth / 2
          break
        case "right":
          this.offsetLeft = residualSpaceWidth
          break
      }
    }
  }

  /**
   * set items position
   * @private
   */
  _setPosition () {
    let opts = this.opts
    // get new item elements
    let $childs = slice(opts.container.querySelectorAll(opts.itemSelector), this.count)
    // console.log(this.count, $childs)
    let len = $childs.length
    // reset this.count value
    this.count += len
    // handle new $item
    let i, $item
    for (i = 0; i < len; i++) {
      $item = $childs[i]
      if (!$item) continue
      $item.style.position = "absolute"
      $item.style.width = this.itemWidth + "px"
      $item.style.display = "inline-block"
      // get columns min value
      let min = Math.min.apply(null, this.columns)
      let index = this.columns.findIndex(val => val === min)
      // set $item position
      $item.style.top = `${min + opts.verticalGutter}px`
      $item.style.left = `${this.offsetLeft + (this.itemWidth + opts.gutter) * index + opts.gutter}px`
      // reset waterfall current column height value
      let itemHeight = $item.offsetHeight
      this.columns[index] = min + itemHeight + opts.verticalGutter
      // update container new min height style
      // opts.container.style.minHeight = Math.max.apply(null, this.columns) + opts.verticalGutter + "px"
    }
  }

  /**
   * container"s items number change
   */
  change () {
    // reset postion, when new item element append to container, or remove
    this._setPosition()
  }

  /**
   * reset
   */
  reset () {
    this.count = 0
    this._init()
    this._setPosition()
  }

  /**
   * preload media items
   * @param arr media source urls array
   * @returns {Promise}
   */
  loadMedia (arr) {
    return new Promise(resolve => {
      if (Array.isArray(arr) && arr.length) {
        let len = arr.length
        let count = 0
        /* eslint-disable */
        arr.forEach(url => {
          loadImage(url, () => {
            count++
            if (len === count) resolve()
          })
        })
      } else {
        resolve()
      }
    })
  }

  /**
   * destroy
   * removeEventListener window resize
   */
  destroy () {
    window.removeEventListener("resize", this._resetClone)
  }
}

export default ZxWaterfall

demo: https://github.com/capricornc...